Subject:
|
Re: Type 5 lines, BFC relevance, and OpenGL
|
Newsgroups:
|
lugnet.cad.dev
|
Date:
|
Mon, 4 Apr 2005 17:33:25 GMT
|
Viewed:
|
2661 times
|
| |
|
|
In lugnet.cad.dev, Mark Tarrabain wrote:
> Slower, you say?
>
> Are you executing the functions in immediate mode? Or using a display list?
>
> Because if you're not using a display list, it's no suprise that it's
> slower.
I'm using a display list. The triangles are drawn inside the display list using
"classic" OpenGL calls (glBegin(GL_TRIANGLES)...glEnd()). The lines are being
drawn inside the display list using vertex arrays. Using vertex arrays to draw
the triangles resulted in a huge performance hit (3x slow-down vs "classic"
OpenGL calls) due to the use of edge flags in the vertex arrays.
> If you are using a display list, however, then I'm at a loss. I guess
> it may not have been that great an idea. This is still good to know.
I'm pretty surprised with the result myself. I think that a really fast video
card would produce different results. On a 6800 Ultra, I suspect that the new
routine would run significantly faster than the CPU-based routine. However, you
do have to realize that the new routine does two things that would normally be
considered bad: it draws a whole bunch more geometry, and it uses an OpenGL
feature that probably hasn't ever been used in a video game (edge flags).
Despite the results, I still think it was a great idea. It's my belief that as
things progress, the video card/CPU performance gap will widen sufficiently for
this to produce noticeably superior performance to the CPU-based way.
On a related note, if anyone out there would be willing to try my modification
on a top-of-the-line (or nearly so) video card, let me know, and I'll send you a
test version of LDView.
> Thanks for the feedback
You're welcome. And thanks for the idea; I really do think the concept is
sound.
--Travis Cobbs
|
|
Message is in Reply To:
 | | Re: Type 5 lines, BFC relevance, and OpenGL
|
| Slower, you say? Are you executing the functions in immediate mode? Or using a display list? Because if you're not using a display list, it's no suprise that it's slower. If you are using a display list, however, then I'm at a loss. I guess it may (...) (20 years ago, 4-Apr-05, to lugnet.cad.dev)
|
9 Messages in This Thread:
 
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
